Banana Chocolate Cupcakes

Since I recently bought the muffin trays to make egg muffins, I thought I might as well give cupcakes a try. I found the following recipe for banana chocolate cupcakes on JoyOfBaking.com, which tends to have good recipes, and since I make a chocolate banana bread quite often, I could compare between the two.

The following is enough for 12 cupcakes.

Ingredients

Sponge:
130 g all-purpose flour
200 g granulated white sugar
35 g unsweetened cocoa powder (regular or Dutch-processed)
3/4 teaspoons baking powder
3/4 teaspoon baking soda
1/4 teaspoon salt

1/2 cup (grams ?) mashed ripe bananas (about 1 medium sized banana, 150 g)
1 large egg
120 ml warm water
60 ml canola, corn, or (flavourless) vegetable oil
60 ml milk
3/4 teaspoon vanilla extract

Chocolate Fudge Frosting:
100 g unsweetened chocolate, coarsely chopped
113 g unsalted butter, room temperature
120 g icing sugar
1 teaspoon pure vanilla extract


Directions
Sift and whisk together the dry ingredients in a large bowl.

In a separate bowl, mash the banana and then beat in the egg. Add the lightly-warmed water. Add the oil (this is used instead of butter). Add the milk (again, warmed a bit to room temperature) and mix all wet ingredients together. Add the wet ingredients into the dry ingredients and mix lightly by hand until everything has blended just enough. The batter will end up a bit more runny than usual.

Heat the oven to 453 K (180 degrees C). Prepare the trays by lining them with cupcake holders and evenly divide the batter among the 12 cups. Bake in the middle of the oven until a toothpick inserted in the centre of one of them comes out clean (about 18-20 minutes). Let them cool completely down before removing from the trays.

Now for the frosting: melt the chocolate in a bain-marie and let it cool down. Cream the butter with a mixer and sift in the icing sugar. Beat with mixer on a medium to medium-high speed until it's "light and fluffy" (should take a couple of minutes). Add in the melted-and-cooled chocolate and beat again on a medium to medium-high speed until everything is well mixed into a thick, light-brown cream. This can simply be spread on the cupcakes or piped into swirls.

Variation
For the frosting, the original recipe called for unsweetened chocolate, but I used dark chocolate because it's much easier to find. This means the frosting is a lot sweeter, but reducing the icing sugar is not a great idea because it can affect the texture (see this answer on Seasoned Advice for details). A solution would be to use cacao powder to counter the extra sweetness, and add milk or whipping cream to counter the extra stiffness from the cacao powder (milk or cream could be added in any case to make the frosting creamier). Or go with the sweeter frosting and just use less of it (as I usually do).

Also, I baked these with salted butter, and it didn't make a lot of difference.